Mold for forming a coreless armature

ABSTRACT

A mold for forming coreless armatures having an upper mold and a lower mold. The lower mold has a mold cavity for receiving a shaft capable of supporting windings of a coreless armature. An elastic ring plate is placed between the upper and lower molds and is adapted for being compressed therebetween. The elastic ring plate is further adapted to contact terminal ends of the windings as they extend outside of the mold cavity, and to seal said mold cavity with the terminal ends extending therefrom.

This is a division of application Ser. No. 908,774 filed Jul. 1,1992,now U.S. Pat. No. 5,304,884 which is a continuation of application Ser.No. 257,470 filed Oct. 13, 1988 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mold and more particularly to a moldfor fabricating coreless armatures.

2. Description of the Prior Art

As is already known, a brushless motor or alternating current motor, forexample, the brushless motor, comprises a magnetic rotor provided with apermanent magnet fixed to the shaft thereof and a stator comprising acylindrical coreless armature which is disposed around the rotor andwhich is provided on a case in the outside thereof. The corelessarmature has a cylindrical shape formed by a plurality of specifiedturns of coil. The various types of coreless armatures available includeone which is formed by a single layer coil and one which is formed bylaminating two or more layers of coil. The latter type generallygenerates an increased output from the motor comprising this type ofarmature.

A prior art example producing this sort of coreless armature is a methodin which armature coils are prepared in advance with a cup-like shape byself-welding wires, a necessary amount of solid resin is placed in amold, the prepared armature coils are placed on the solid resin andcovered with another mold so that the armature coils are molded into adesired shape and are fixed by charging the solid resin in the moldunder heating (see, for example, Japanese Patent Laid-OpenNo.125061/1980).

Another example of prior art is a technique in which an attempt is madeto reduce the thickness of an armature by adopting an arrangement inwhich coils are bent into U-shaped forms and disposed in two layersaround a cylinder, one of the two layers having a larger diameter thanthe other in an overlapping portion (see, for example, Japanese UtilityModel Laid-Open No.75702/1978).

Another type of armature is known which comprises a cylindrical armaturewinding formed by producing a plurality of winding units and thencombining these winding units (see, for example, Japanese Utility ModelPublication No. 31176/1981).

A technique concerning a molded stator has also been disclosed inJapanese Utility Model Laid-Open No.55906/1976 in which an outgoing leadwire for each of the phase coils and an outgoing lead wire for a hallelement, provided for the purpose of detecting the positions of rotormagnetic poles, are connected to a printed board which is provided onthe surface at one end of a cylindrical stator coil to form anindependent structure as a unit. The Cylindrical armature disclosed inthis publication is formed by inserting a plurality of armature windingswhich are wound or shaped in advance into a desired shape in a mold, andburying the windings in the heated resin in a semi-solidified statewhich is charged under pressure through a gate provided at an opening ofthe mold to be molded into a cylindrical form as a unit. The mold usedfor forming the bore portion of the cylindrical armature is generallyformed as a unit from one end of the armature to the other end thereof,with a draft being provided so that the armature fixed by the resin canbe easily separated from the mold. The above-described conventionalcylindrical armature therefore has the bore inclined in one directionfrom one end to the other end thereof which is formed by the draft ofthe mold.

Coreless multi-layer armatures of the type formed by laminating two ormore layers of coil have the problems described below with respect tothe production thereof.

1. Although it is desirable that the linear portion of the winding of acoil which functions to generate torque is as large as possible, if thisrequirement is satisfied, the size of an armature is increased. In thiscase, even though the thickness of the armature can be reduced by adistributed winding in which conductors are arranged around thecircumference of a cylinder without any gaps, anti-torque is producedaccording to the arrangement of the conductor. If a concentrated windingin which conductors are concentrated at portions near the boundarybetween magnetic poles is employed, even though no anti-torque isproduced, there is a problem in that the thickness of the armature hasto be increased.

2. A process of producing an armature in which coils arranged in acylindrical form are fixed by molding with resin using a mold has thefollowing problems:

(1) Although fixing of coils is perfomed by molding in a mold after theyhave been shaped into a cylindrical form so that they do not loosen, thecoils are likely to lose their shape or become damaged when the coilsare placed in the mold which is then closed.

(2) A means for fixing the coils in the mold by charging melted resinunder pressure exhibits excellent efficiency in terms of mass productionbut involves the problem that the coils are sometimes deformed by thepressure of the resin used.

(3) Methods for resolving the problem described in (2) include a methodin which coils are placed in a mold and resin which is liquid at roomtemperature is injected into the mold under reduced pressure and thensolidified by heating, and a method in which solid resin is placed in amold together with coils and then melted under pressure so as topenetrate between the coils. Such methods, however, involve certaindisadvantages since these methods require many molds and much workingtime and thus lack efficiency in terms of mass production.

The technique disclosed in Japanese Patent Laid-Open No. 125061/1980also has the following problems:

1. There is a possibility of producing deviations in the shape of coilsor damaging the coils during the shaping of the coils that is performedby covering them with a mold.

2. It is very difficult to produce a large number of armatures.

The technique disclosed in Japanese Utility Model Laid-Open No.75702/1978 also has the problems that coils are easily broken becausethey are bent in a complicated manner and that resin molding isextremely difficult.

The armature described in Japanese Utility Model Publication No.31176/1981 must be provided with an insulating sheet to provideinsulation between the iron core of a stator and the winding of thearmature.

In the armature described in Japanese Patent Laid-Open No. 125061/1980or an armature formed by pressure injection, portions of the winding ofthe armature which adhere to the surface of the mold are produced whenthe heated resin is poured or semi-solidified resin is-injected underpressure, and, when the armature is separated from the mold aftersolidification of the resin, the winding of the armature adhering to themold is exposed to the air on the sides of the armature and on the endsurface opposite to the gate through which the resin is injected. Whenthe thus-formed armature is combined with a core or a case, therefore,the exposed portions of the winding of the armature are in some casesrubbed and produce short circuiting owing to vibrations caused byhigh-speed rotation during the use of the armature. Projecting edges areproduced on the armature during assembly thereof and may sometimes bringabout short circuiting upond contacting the core or the case. Theabove-described armature therefore involves the problems that aninsulating member such as an insulating sheet or the like must beprovided for the purpose of preventing any short circuiting and that thearmature cannot be precisely combined with the core or the case becauseof the presence of projecting edges or burrs.

A revolving electric device of the type in which a printed board isfixed to one end of an armature and the terminals of the coils of thearmature are connected to the printed board, as described above in theprir art, is generally of the type in which the terminals of thearmature coils emerge from the end of the armature. In this case, inorder to allow soldering of the terminals of the armature coils to theprinted board, a hole or notch through which the terminals of thearmature coils can be passed must be provided in the printed board, orthe terminals of the armature coils must be held between the printedboard and the end of the armature and extended to the side of theprinted board. A hole or notch must therefore be provided in the printedboard and this results in limiting the space available for printedwiring, as well as producing a problem with respect to the strengththereof. In order to remove this problem, the area of the printed boardhas to be increased, but since an increase in the area of the printedboard runs counter to the desire to decrease the size of the armature,no attempt can be made to reduce the size of the latter in theabove-described prior art.

In addition, in the above-described prior art, since the end from whichthe terminals of the armature coils emerge has a flat surface, theterminals of the armature coils are brought into contact with otherparts or bent at their roots during work, resulting in a great risk ofthe breaking of wires. The operator therefore has to use excessiveconcentration in operating the armature and this greatly strains thenerves.

Furthermore, when the terminals of the armature coils are extended tothe side of the printed board, the terminals of the armature coils arebent in a complicated manner or broken between the printed board and theend of the armature, resulting in the possibility of breaking the wires.There is therefore a disadvantage in that the operator's nerves aregreatly strained.

The above-described cylindrical armature of the prior art also involvesa problem in that the bore of the armature is inclined in one directionfrom one end to the other and thus shows a great difference in diameterbetween its two ends. The gap between the rotor and the winding in thestator is thus enlarged, adversely affecting the performance of thearmature, particularly rotational torque. There is also a problem inthat the armature winding inserted into the mold may be pushed on andadhered to the mold which forms the bore surface of the armature by theresin injected into the mold owing to pressure injection of the moldingresin, and the armature may thus be formed with the winding exposedthrough the molding resin. When such an armature is assembled as arevolving electric device, the exposed portion of the armature windingthereof causes the shape of the armature to be changed to project towardthe rotor side owing to vibrations and heat generated during high-speedrotation of the revolving electric device, and thus adversely affectsthe function of the armature.

SUMMARY OF THE INVENTION

An object of the present invention to provide a mold used in themanufacture of a coreless armature and avoid the aforementioned problemfound in the prior art. The mold of the present invention, is used inthe manufacture of a coreless armature comprising coils which are woundwith a given phase in two or more layers around the circumference of acylinder and which is molded into a cylindrical form by using resin, thecoil pitch of the phase coils in each of the layers is set to be 125% orless of the pole pitch, and the gap between the respective phase coilsin any one of the layers being so disposed as to face the internal spaceof each of the phase coils of the other layer being in contact with thatlayer.

A method of producing the coreless armature configured as describedabove which is formed by winding coils with a given phase in two or morelayers around the circumference of a cylinder and molding them into acylindrical form using resin is characterized by disposing the gapbetween the respective phase coils in any one of the two or more layersso as to face the internal space of each of the phase coils of the otherlayer being in contact with that layer and by charging resin underpressure into the internal space of each of the phase coils of the otherlayer through the gap between the respective phase coils during moldingof the armature.

The molding of the periphery of the coreless armature configured asdescribed above is preferably performed by using a mold with a moldregistering surface which is so formed as to be parallel with the axialdirection of the armature.

In the coreless armature configured as described above, the resin isinjected and charged in a well-balanced manner into the space on theinside of the other layer facing the gap between the respective phasecoils in each of the layers and through the gap.

Furthermore, when the periphery of the armature is molded, the mold canbe slowly registered and closed in the radial direction.

The mold of the present invention is used in a process for producing anarmature for a revolving electric device which comprises leading out theterminal of each armature winding from the resin used for molding thearmature to the outside thereof by using a transfer molding method,particularly a low-pressure transfer molding method. To this end, themethod is characterized in that each of a plurality of armature windingswhich are wound in advance to form a desired shape is placed at a givenposition in a mold used for molding, the terminal of each of thearmature windings is lead out to the upper surface of the mold and thenfixed under pressure through an elastic ring member, and a syntheticresin material used for molding is charged into a space which is formedby the inner wall of the elastic ring member, and the mold and thearmature windings.

Since the low-pressure transfer molding method is used in themanufacture of the coreless armature a thermosetting resin such as epoxyresin which is raw resin is kneaded with additives and then solidified,and the solidified material is heated in the mold for molding andpressed so that the armature windings previously placed at the givenpositions in the mold are encased and fixed in place by the resin.During this molding, the way in which the terminals led out from each ofthe armature windings in the mold is important and it is also criticalthat only the terminals are led out from the resin of the armature aftermolding. In the present invention, an elastic resin plate having heatresistance is used so that the terminals are arranged between the resinplate and the mold and buried in the elastic resin plate because theelastic resin plate is appropriately deformed by compression betweenupper and lower molds when these molds are closed, whereby any leakageof the material used for molding can be prevented. After the armaturehas been molded, the terminals alone can be led out from the resin ofthe armature by simply opening the molds and removing the elastic resinplate. An armature made with the mold of the present invention can beproduced by a transfer molding method, particularly a low-pressuretransfer molding method, with a high level of productivity beingmaintained, and which requires no insulating member even if the armaturehas exposed portions in the armature windings, and which also can beprecisely assembled without being affected by projecting edges and burrsproduced by molding. To this end, a plurality of armature windings whichare previously wound to form a desired shape are integerally buried in amolding resin material by molding to form a cylindrical shape, andconvex portions are provided on the sides of the armature which arefixed to the core or the case of a revolving electric device so as toserve as receiving surfaces when the armature is fixed to the core orthe case, as well as to able to provide a gap between the armature andthe core or the case.

An object of the present invention is to produce an armature for arevolving electric device which is reduced in size and in which breakingof the terminals of armature coils is prevented. To this end, in anarmature for a revolving electric device comprising a plurality ofarmature windings which are wound in advance to form a desired shape andwhich are integrally buried in a molding resin material by molding toform a cylindrical shape. The terminal of each of the armature windingsis led out from a groove provided near one end of the armature so thatan attempt can be made to reduce the size of the, armature and the riskof breaking of any of the terminals of the armature coils can becompletely eliminated. In addition, since none of the terminals of thearmature coils is either broken or rubbed during assembly of thearmature because it is held between a printed board and the end of thearmature, the level of strain imposed on workers can be significantlylowered.

To achieve this object, in an armature for a revolving electric devicecomprising a plurality of armature windings which are each wound inadvance to form a desired shape and which are integrally buried bymolding in a molding resin material to form a cylindrical shape, and aprinted board which is provided at one end of the cylindrical moldedshaped, a groove through which the terminals of the armature windingsare led out is provided in the periphery of a cylindrical molded shapeand the external diameter of a portion for introducing the terminals ofthe armature windings in the periphery of the cylindrical molded shapeis made small so that a space for introducing the terminals of thearmature windings is formed between the the cylindrical shape and theinternal periphery of the body of the revolving electric device, wherebyan attempt can be made to reduce the size of the armature.

The present invention can be used to fabricate an armature for arevolving electric device in which there is no difference in theinternal diameter formed by the draft of a mold and no portion of thearmature windings exposed to the molding resin. To this end, in anarmature for a revolving electric device comprising a plurality ofarmature windings which are each wound in advance to form a desiredshape and which are integerally buried by molding in a molding resinmaterial to form a cylindrical shape, the bore portion of the armatureis formed by a resin film which is composed of the molding mesinmaterial and which has a surface outwardly inclined from an appropriateposition on the bore surface toward both ends thereof, whereby the gapbetween a rotor and a stator can be reduced and exposure of the armaturewindings can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plane cross section of an embodiment of a coreless armatureto which the present invention relates;

FIGS. 2a, 2b and 2c are explanatory views of principal portions of theembodiment shown in FIG. 1;

FIGS. 3a, 3b are explanatory views of a process for producing anarmature;

FIG. 4 is a sectional view of a mold used for charging resin;

FIG. 5 is an explanatory perspective view of the state wherein a dividedmold is opened;

FIG. 6 is a sectional view of the configuration of an apparatus forperforming a method of producing an armature for a revolving electricdevice of another embodiment to which the present invention relates;

FIG. 7 is a perspective view of the state wherein armature windings areinserted into an lower mold for molding;

FIG. 8 is a perspective view of armature windings wound around the shaftof a mold;

FIGS. 9 to 11 are sectional views of modified examples of the method ofthe present invention;

FIG. 12 is a partially sectional side view of armature windings producedby the method shown in FIG. 11;

FIG. 13 is a partially sectional front view of another embodiment of thearmature for a revolving electric device

FIG. 14 is a front view of still another embodiment of the armature fora revolving electric device;

FIG. 15 is a front view of a further embodiment of the armature for arevolving electric device;

FIG. 16 is a half sectional front view of a still further embodiment ofthe armature for a revolving electric device;

FIG. 17 is a sectional view taken along the line I--I of FIG. 16 asviewed from the arrow shown in FIG. 16;

FIG. 18 is a sectional front view of another embodiment of a revolvingelectric device equipped with an armature;

FIG. 19 is a perspective view of still another embodiment of thearmature;

FIG. 20 is a sectional front view of a principal portion of the armatureshown in FIG. 19;

FIGS. 21 and 22 are drawings of a further embodiment of the armature, inwhich FIG. 21 is a sectional view of the armature and FIG. 22 is anexplanatory view of a state of the armature molded; and

FIG. 23 and 24 are drawings of a still further embodiment of thearmature, in which FIG. 23 is a sectional view of the armature and FIG.24 is an explanatory view of a state of the armature molded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Embodiments of the present invention are described in detail below withreference to the drawings.

FIG. 1 shows an embodiment of a coreless armature 1 which can be madeusing the mold of the present invention. This drawing shows as anexample an armature which is used for a three-phase brushless motor andwhich comprises six coils.

As shown in the drawing, the coreless armature 1 comprises armaturecoils in two layers (the number of layers may be two or more and is notlimited to two) comprising external layer coil 2 and internal layer coil3 and has a cylindrical form. Phase coils 2a, 2b, 2c in three phases ofthe exteranl layer coil 2 are so provided as to respectively form gaps4, 5, 6 therebetween (see FIG. 2c). Similarly, phase coils 3a, 3b, 3c inthree phases of the internal layer coil 3 are also provided so as torespectively form gaps 7, 8, 9 therebetween. The gaps 4, 5, 6 betweenthe respectively phase coils 2a, 2b, 2c in the three phases of theexternal layer coils 2 are so disposed as to face the internal spaces10, 11, 12, respectively, of the phase coils 3a, 3b, 3c in the treephases of the internal layer coil 3. The gaps 7, 8, 9 are also disposedso as to face the internal spaces 13, 14, 15, respectively, of theexternal layer coil 2.

Each of the phase coils 2a, 2b, 2c, 3a, 3b, 3c comprising the externallayer coil 2 and the internal layer coil 3 is formed into the shapeshown in FIG. 2a (showing as an example the phase coil 2a of theexternal layer coils 2) by means of a winding machine (not shown) usingself-welding wires. Reference numerals 2d and 2c denote coil pieces.

The thus-formed phase coils 2a to 2c and 3a to 3c are bent along thecircumference of a cylinder to form an arch-like shape with a givenradius R and is disposed as the coils 2, 3 in the two layers to from thecylindrical coreless armature 1. The angle θ m₁ (corresponding to thecoil pitch) facing the coil width (coil pitch ) of each of the phasecoils (for example, the phase coil 2a) which are bent to form arch-likeshapes with the given radius R is set to be about 110° . The angle θ m₂facing the internal periphery of each of the coil pieces 2d and 2c isset to be 65° to 75° . Since the angle corresponding to the pole pitchis 90°, the angle corresponding to the coil pitch of each of the phasecoils in this embodiment is set to a value of about 1.2 time the polepitch. In other words, the width of each of the coil pieces 2d, 2e is soset as to have an extent of about 20° toward the adjacent coil and about20° toward the center of the coil from the boundary between magneticpoles seving as a center.

The corelss armature 1 configured as described above is adhered to theinside of the case (not shown) of a motor composed of a magneticsubstance. The case forms magnetic paths in combination with a yoke 17of the side of a rotor 16. The yoke 17 is fixed to a shaft 18 andprovided with a permanent magnet 19 which is fixed thereto and dividedinto four equal portion along the circumference of a cylinder to formthe four-pole rotor 16.

A description will now be given of a method of producing the corelessarmature configured as described above.

The three phase coils 3a, 3b, 3c which are formed as shown in FIG. 3aare first prepared, then arranged substantially at equal intervals alongthe periphery of an internal mold 21 on a base 20 and temporarily fixedby a tape (not shown) to form the internal layer coil 3. In the drawing,reference numeral 22 denotes the terminal of each coil.

As shown in FIG. 3, the three phase coils 2a, 2b, 2c comprising theexternal layer coil 2 are then respectively arranged on the externalsurface of the internal layer coil 3 and temporarily fixed by a tape inthe same way as the internal layer coil 3.

The phase coils 2a to 2c of the layer ocil 2 and 3a to 3c of the layercoil 3 are positioned so as to be symmetrical in the peripheraldirection of each of the layers. Such positioning causes the gaps 4, 5,6 between the respective phase coils 2a to 2c and the gaps 7, 8, 9between the respective phase coils 3a to 3c to be substantailly the sameas each other. This positioning is performed so that the gaps 4, 5, 6between the respective phase coils 2a, 2b, 2c and the gaps 7, 8, 9between the respective phase coils 3a, 3b, 3c in the layer coils 2, 3respectively face the corresponding internal spaces 10, 11, 12, 13, 14,15 of the phase coils.

As shown in FIG. 4, an outer mold 23 is then placed on the coils whichare positioned as described above. The outer mold 23 for molding thearmature has a divided form comprising two mold pieces 23a, 23b, asshown in FIG. 5. The mold registering faces 30, 31 of the molds pieces23a, 23b are so formed as to be parallel to the axis of the corelessarmature 1. When the mold 23 is placed on the coils, the mold pieces23a, 23b are registered by using the mold registering faces 30, 31.

After the outer mold 23 has been registered and closed, molten resin isinjected under pressure into the mold from the resin injection hole 33of the resin injection molding machine 32 shown in FIG. 4. The resininjected flows to the layer coils 2, 3 in the following path of inflow:The resin is caused to flow into the mold while passing through the gaps4, 5, 6, 7, 8, 9 between the respective phase coils in the layers shownin FIG. 1, the resin flowing into the gaps 4, 5, 6 of the external layercoil 2 being caused to flow and charged into the corresponding internalspaces 10, 11, 12 of the phase coils 3a, 3b, 3c of the internal layercoil 3, and the resin flowing into the gaps of the internal layer coil 3being caused to flow and charged into the corresponding spaces 13, 14,15 of the phase coils 2a, 2b, 2c of the external layer coil 2, as shownby the arrows in the drawing.

During the above-described process, the external layer coil 2 and theinternal layer coil 3 are fixed by transfer molding using the resin toobtain the coreless armature 1.

As described above, in the present invention, since the phase coils 2ato 2c of the external layer coil 2 and the phase coils 3a to 3c of theinternal layer coils 3 each have the coil pitch (the width of each ofthe phase coils) which is set to be 1.25 times or less the pole pitchand are arranged in two layers to form a cylindrical shape and thensubjected to transfer molding, the invention displays the followingeffects:

(1) Since the conductors of the coils are arranged around the peripherywith good efficiency, the output per unit area of a motor is increased.

(2) The use of transfer molding facilitates mass production ofarmatures.

(3) Since the coil pitch (the width of each phase coil) of each of thephase coils 2a to 2c and 3a to 3c is set to be 1.25 times or less onepole pitch, no or only small anti-torque is produced.

(4) Since the gaps 4, 5, 6 between the respective phase coils 2a to 2cand the gaps 7, 8, 9 between the resepective phase coils 3a to 3c aresymmetrically placed in each of the two layers, and the resin is passdthrough the gaps 4, 5, 6, 7, 8, 9 and caused to flow and charged intothe internal spaces 10 to 12 and 13 to 15 which are so disposed as toface the corresponding gaps 4, 5, 6, 7, 8, 9, the path of inflow of theresin can be secured. In addition, since the pressure of the resin iswell balanced in the peripheral direction during injection of the resinand the coils are held by the external mold 23 in the radial directionthereof, the coils is neither deformed nor demaged.

(5) Since the mold registering faces 30, 31 of the external mold 23 areso formed as to be parallel with the axial direction of the corelessarmature 1, the coils can be slowly held in the radial direction,resulting in no deviation in the positions of the coils.

(6) Since the layer coils 2, 3 are fixed by the resin, the strength ofthe armature 1 can be secured.

FIG. 6 is a sectional view of the configuraiton of a mold of anotherembodiment to which the present invention relates, and FIG. 7 is aperspective view of a lower mold for molding.

A plurality of armature windings 101 are first wound around a shaft 102which is a member of a lower mold 105, as shown in FIG. 8a or 8b. Thelower mold 105 has an opening in an upper portion thereof and a concaveportion for receiving the shaft 102 around which the armature windings101 are wound. On the opening of the lower mold 105 is disposed anelastic resin ring plate 103 (for example, made of silicone rubber)having heat resistance which is tolerable molding by thermosettingresin. In other words, this elastic resin ring plate 103 is interposedbetween the lower mold 105 and a runner plate 107 of an upper mold 113so as to be deformed by compression during closing of these moldsbecause the runner plate 107 is brought into contact with the uppersurface 109 of the lower mold 105 and the upper surface of 110 of theshaft 102 which have the same height. The upper mold 113 comprises therunner plate 107 and a fixed plate 114 which is provided on the upperside thereof and which has an opening 115. This opening 115 forms achamber, i.e., a pot, in combination with a concave portion 101bprovided in the runner plate 107. The runner plate 107 has a pluralityof transfer injection ports (gates) which are provided in a circularform in the surface thereof being in contact with the lower mold 105 andwhich communicate with the pot. A solid material (tablet) which isformed by kneading thermosetting resin of raw resin-such as epoxy resinwith additives and solidifying the obtained mixture can be thereforecharged into the pot, softened by heating, and pressed by a plunger 117so as to be transferred to the void formed in the lower mold 105.

The gate 108 provided in the runner plate 107 is so disposed as to bepositioned in the inside of the elastic resin plate 103.

A description will now be given of a method of molding in due orderbelow.

The shaft 102 around which the armature windings 101 are wound is firstinserted into the concave portion of the lower mold 105. The terminals104 led out from the plurality of armature windings 101 are thendisposed in a slit which is provided in the wall of the periphery in theupper surface of the lower mold 105. The elastic resin ring plate 103having an external diameter equal to the internal diameter of theabove-described wall is then placed on the terminals 104. When a moldingmachine is started, the space between a stage 106 on which the lowermold 105 is mounted and the runner plate 107 of the upper mold 113 isreduced so that the lower suface of the runner plate 107 is brought intocontact with the upper surface 109 of the lower mold 105 and the uppersurface of 110 of the shaft 102 while deforming the elastic resin plate103 by compression. The terminals 104 are therefore buried in theelastic resin plate 103, without any leakage of the molding resininjected from the gate (transfer injection hole) 108 taking place. Afterthe molding resin has been set, the molding molds are opened, and theelastic resin plate 103 is removed. An armature charged with the moldingmaterial with the terminals 104 emerging therefrom can be obtained by,for example, inserting an ejection pin from a hole 111 provided in alower portion of the lower mold 105 to push the shaft 102. When theshaft 102 is then removed, a complete armature can be obtained.

In the aforemetioned embodiment, although the lower mold 105 isseparated from the stage (mold) of the molding machine, it is matter ofcourse that the lower mold 105 may be formed in conbination with thestage. In cosideration of the risk of damaging the shaft 102 owing togreat force generated at closing of the molds, a burr or a thin film maybe formed between the surface 110 of the shaft 102 and the runner plate107 so that the closing force acts on only the surface 109 of the mold105, and the burr may be removed after molding. The shaft may also beformed in combination with the lower mold 105.

FIG. 9 shows an example in which the elastic resin plate 103 is fixed tothe runner plate 107 and the other members are the same as those shownin FIG. 6. This example can remove the processes for attaching anddetaching the elastic resin plate 103 and thus reduce the number ofprocesses for each shot.

FIG. 10 shows an example in which the terminals of the armature windings101 are placed on the upper side of the elastic resin plate 103. Thisexample enables the terminals 104 to be led out from the end of thearmature after molding and a certain degree of freedom to be obtainedwhen the armature is matched to the internal structure of a revolvingelectric machine.

FIG. 11 shows an example in which the terminals 103 are held between twoelastic resin plates 103a and 103b and in which the internal diameter ofthe elastic resin plate 103 is smaller than the diameter of a hole inwhich the armature windings 101 are inserted. A ring groove 118 is alsoprovided in the runner plate 107. FIG. 12 shows the shape of thearmature which is molded by a mold having the structure of this example.In this example, the terminals 104 of the armature windings 101 are ledout from the wall of the concave portion 119 and thus the roots of theterminals are not easily brought into contact with fingers or otherparts during work, with the effect of preventing any breaking of wiresresulting.

FIG. 13 is a partically sectional front view of still another embodimentof an armature for a revolving electric device to which the presentivnention relates. In the drawing, reference numeral 201 denotes anarmature having a plurality of armature windings 202 which are fixed bya resin material 203 for molding to be buried therein. The armature 201has convex ring portions 205, 206 which have the same height(thickness), which are respectively provided at both ends 201a, 201b ofthe periphery 204 thereof by integeral molding using the above-describedresin material. The armature 201 also has a concave ring portion 208which abuts against a case (not shown) and which is provided byintegeral molding at an end 201cof the armature 201 opposite to a gateportion 207 through which molding resin is injected in the same way asthat described above. Referene numeral 209 denotes the terminals ofarmature windings 202 which are led out from the molding resin 203, andreference numeral 210 denotes exposed portions of the armature windings202 which are adhered to the suface of the mold by being pushed by themolding resin 203 injected and exposed through the surface of the resin203.

In the armature 201 having the structure of this embodiment, the convexring portions 205, 205 provided in the periphery 204 thereof can preventthe exposed portions 210 of the armature windings 202 in the periphery204 thereof from being brought into contact with a core or a case whenthe armature 201 is combined with the core or the case. The concave ringportion 208 which is provided at the end 201c of the armature 201 canalso prevent the exposed portions of the armature windings 202 at theend 201c from being brought into contact with the case. In additon, theconvex ring ortions 205, 206 and 208 causes projecting edges, burrs orthe like which are produced during molding by the molds to give onlysmall effects when the armature 201 is combined with the core or thecase.

As described above, the armature of this embodiment enables a rovolvingelectric device which requires no insulating member such as aninsulating sheet between the armature and the core or the case to beobained. The armature can be also precisely combined with the core orthe case without being affected by projecting edges or burrs.

The convex ring portions 205, 206 and 208 may be provided by mountingconvex portions made of a non-conductive member on the armature. In thiscase, the same function and effect as those described above can beexhibited.

FIG. 14 is a front view of a further embodiment of an armature for arevolving electric device to which the present invention relates.

An armature 220 of this embodiment comprises convex ring portions and aconvex abutting ring portion which have shapes different from the convexring portions 205, 205 and the convex abutting ring portion 208 of theabove-described embodiment. Since other members are the asme as those ofthe above embodiment, they are denoted by the, same reference numeralsand are not described below.

The armature 220 has a plurality of convex portions 221, 222 which areprovided near the ends 201a, 201b of the periphery 204 thereof byintegral molding using the above-described molding resin material, theseconvex portions 221, 222 being formed as to have the same height(thickness), whereby exposed portions 201 of armature windings 220 (notshown) exposed from the periphery 204 of the armature 220 can beprevented from being brought into contact with a core or a case. Thearmature 220 also has a plurality of convex portions 223 which each havea boss-like form, which abut against the case (not shown) and which areprovided at the end 201c of the armature 220 by integral molding so thatthe exposed portions 201 of the armature windings (not shown) exposed atthe end 201c can be prevented from being brought into contact with thecase. On one (specified) of the abutting convex portions 223 is provideda projecrion 224 used of positioning the case and the armature 220.Although this embodiment shown in the drawing has the convex portions221, 222 and 223 which each comprise four portions provided at equalintervals, the numer of portions is not limited to four, and the convexporions 221, 222 and 223 may be appropriately provided.

As described above, the armature of this embodiment can display the samefunction and effect as those described above.

FIG. 15 is a front view of a still further embodiment of an armature 301to which the present invention relates.

As shown in the drawing, the armature 301 comprises a plurality armaturecoils (referred to as armture coil windings and not shown in thedrawing) which are wound in advance to form a desired form and which areintegerally molded into a cylindrical shape by a synthetic resinmaterial 302 used for molding.

A ring groove 304 which intersects at right angles the axial directionof the armature 301 and which has a given depth is provided at aposition near the end 303 thereof. The temrinals 305 of the armaturecoils which are buried in the synthetic resin material are led out tothe outside thereof. Reference numeral 305adenotes the roots of theterminals of the armature coils.

The armtaure 301 configured as described above exhibits the followingeffects:

(1) Since there is no need of providing a hole or a notch which preventthe reduction in the size of the armture, the area of the printed boardcan be set to a minimum necessary size, i.e., a minimum size in view ofa space available for printed wiring and the strength thereof, wherebyan attempt can be mae to reduce the size of the armature 1.

(2) Since the roots 305a of the terminals 305 of the armature coils areled out from the groove which is formed so as to be one step lower thanthe periphery of the armature coils 301, the terminals 305 of thearmature coils are not forced to be bent at the roots 305a thereofduring assembly. As a result, none of the roots 305a of the terminals305 of the armature coils is either brought into contact with otherparts or repeatedly folded during work such as assembly. It is thereforepossible to secure that the risk of breaking wires is prevented duringwork and to significantly reduce the nerve strain of the worker duringwork.

(3) Since the terminals 305 of the armature coils need not be extendedto the side of the printed board, the terminals 305 of the armaturecoils are not held between the printed board and the end 303 of thearmature, and thus they are neither folded in a complicatd manner norbroken between the printed board and the end 303 of the armature. As aresult, in the same manner as described above in (2), it is possible tosecure that the risk of breaking the terminals is prevented and tosignificantly reduce the nerve strain of the worker.

FIGS. 16 and 17 show another embodiment of the armture 301 to which thepresent invention relates, FIG. 6 being a front view with sectioned lefthalf and FIG. 7 being a sectional view taken along the line I--I of FIG.16 as viewed from the arrow shown in FIG. 16.

In this embodiment, the groove 304 shown in FIG. 15 is so formed as tohave a plane cross section of a waveform so that the terminals 305 ofthe armture coils (armature windings) are led out from the troughs304aof the waveform. The diameter of the periphery formed by the crests304b is set to substantially the same as the external diameter of thearmture 301. As a matter of course, the form of the plane cross sectionof the goove 304 is not limited to teh waveform. Since other members arethe same as those shown in FIG. 15, they are denoted by the samereference numerals and are not described below.

In the aforementioned configuration, since the molded portion (theportion of synthetic resin used for molding) which forms the crests 304bserves as a reinforcing portion, it is possible to secure that anyreduction in the mechanical strength of the armature 301 caused byforming the groove 304 is prevented. Since other effects are the same asthose achieved by the above-described embodiments, they are notdescribed below.

FIG. 18 is a sectional front view of a revolving electric device 401equipped with the armature to which the present invention relates. Inthis drawing, reference numeral 402 denotes a case; reference numeral403, molding synthetic resin which is used for fixing by molding aplurality of armature coils (armature windings) 404 which are wound inadvance to form a desired shape so as to be buried therein to form acylindrical armature; reference numeral 405, the terminals of thearmature coils; reference numeral 406, a printed board having connectionbetween the armature coils and the terminals 405 ; reference numeral408, a rotor; and reference numeral 409, a bearing.

A ring groove 410 is formed in the periphery of a portion of moldedsynthetic resin 403abetween the armature coils 404 and the printed board406, the external diameter of the portion of the molded synthetic resinportion 403a that is closer to the printed board 406 than the groove 410is set to a value smaller than the diameter of the internal periphery ofa case 402. In other words, although the external diameter of theperiphery of the molded portion 403b of the armature coils 404 in thesynthetic resin portion is set to substantially the same as the internaldiameter of the case 402 so as to be brought into contact with theinternal periphery of the case 402, the external diameter of the portionof the molded synthetic resion portion 403 closer to the printed board406 than the ring groove 410 is set to a value smaller than thatexternal diameter of the molded portion 403b. There is therefore asuitable space 411 formed between the internal periphery of the case andthe periphery of the portion of the molded synthetic resin portion 403closer to the printed board 406 than the groove 410. This space 411 maybe set to have a size which makes it possible to pass the terminals 405of the armature coils 404 therethrough.

Since the external diameter of the printed board 406 is set tosubstantailly the same as the external diameter of the portion of themolded synthetic resin portion 403 closer to the printed board 406, aspace 411 is also formed between the printed board 406 and the internalpheriphery of the case 402.

As the above-described configuration enbales the terminals 405 of thearmature coils 404 to be connected to a connetion portion 407 of theprinted board 406 through the ring groove 410 and the space 411, theterminals 405 of the armature coils 404 are not rubbed by the case (or acore). As a result, it is possible to ensure that any occurrence ofbreaking of the terminals 405 of the armature coils 404 and shortcircuit thereof are prevented and to make an attempt to improve thequality and reliability of of the revolving electric machine. Inaddition, since there is no need of providing a hole or a notch forleading out the terminals 405 of the armature coils 404 in the printedboard 406, the size of the printed board 406 can be set to a minimumnecessary size, i.e., a minimum size in view of a space for printedwiring and and the strength thereof. As a result, it is possible to mekean attempt to reduce the size of the armature (make the armaturecompact) in the revolving electric machine 401.

FIGS. 19 and 20 show a still other embodiment of the present invention.This embodiment has a fin portion 420 for guiding the printed board 406which is provided in the external periphery of the portion of the moldedsynthetic resin portion 403acloser to the printed board 406. The finportion 420 is provided in the external periphery of the moldedsynthetic resin portion 403aexcept for the poriton for introducing theterminals 405 of the armature coils 404. The external diameter of thefin portion 420 is set to the same as or a value smaller than theexternal diameter of the molded portion 403bof the armature coils 404.The axial height of the armature is so set that the end of the maratureis above the end of the molded synthetic resin portion 403a, whereby theprinted board 406 can be guided. Since tther members are the same asthose shown in FIG. 18, they are denoted by the same reference numeralsand are not described below.

The above-described configuration exhibits the function and the effectsattained by the aforemetioned embodiments, as well as having an effectof improving the workability of setting and assembling the printed boardat a given position.

FIG. 21 is a sectional view of a further embodiment of an armature for arevoling electric device to which the present invention relates.

In the drawing, reference numeral 501 denotes an armature comprising aplurality of armature windings 502 which are wound in advance to form adesired shape and are integerally buried in molding resin 503 to form, acylindrical. The armature 501 also has a resin film 506 which is formedin the internal periphery 504 of the armature 501 in such a manner thatit becomes thick substantially in a centeral portion 504 and graduallythin in the directions from substanitally the central portion 504 toboth ends 501a and 501b of the armature 501 so that only small portionsat the both ends 502a, 502b of the armature windings are exposed fromthe resin film 506. Reference numeral 507 denotes the terminals of thearmature windings led our from the molding resin 503.

A description will now be given of the formation of the above-describedarmature 501 with reference to FIG. 22.

The plurality fo armature windings 502 which are wound in advance toform a desired shape are first inserted into a concave portion 512 whichis formed by a side mold frame 509, an upper mold 510 and a lower mold511. The upper mold 510 and the lower mold 511 form the bore surface 504fo the armature 501. Each of the upper mold 510 and the lower mold 511has a draft which is formed so that the diameter thereof graduallydecreases toward the end thereof and so as to form a space 512 having atriangular sectional form between the armature windings 502 and each ofthe molds 510 and 511 during closing the molds. Reference numeral 513denotes butting faces of the two molds 510, 511 which are adhered toeach other when the molds are closed. The openings of the molds arerespectively provided with elastic ring member 514, 515 which each haveheat resistance and are made of silicone rubber so that the terminals507 of the armature windings 502 are held between these elastic ringmembers 514, 515. In this state, a projection 510 for positioning whichis provided on the upper mold is engaged with a concave portion 516b forpositioning which is provided in a runner plate 516, and molding resin513 is injected into the spaces 512 through a gate 517 provided in therunner plate 516. The armature windings 502 are buried in the moldingresin 513 which is charged in the spaces 512 with the molded resin film506 being formed around the entire bore suface 504 of the armature 501and having the same shape as that of the spaces 512 formed by thearmature windings 502, the upper mold 510 and the lower mold 511. Whenthe elastic resin plates 514, 515 are then removed, as well as the moldsbeing removed, the armature 501 can be obtained.

In the armature of this embodiment, since the bore surface of thearmature is formed by the upper and lower molds so that the bore surfaceis outwardly inclined from substantially the central portion to bothends of the armature windings by the draft of each of the molds, thespace between a rotor and a stator formed by the draft can be reduced ascompared with conventional armatures, and the quality of the armaturecan be improved. In addition, since the both ends of the armaturewindings are respectively held by the upper and lower molds during theinjection of the molding resin, only small portions at the both ends areexposed from the molding resin and other portions are not exposedtherefrom, resulting in no loss of the function of the armature.

Although the above-described embodiment concerns the case in which thebutting faces of the upper mold and the lower mold are substantially atthe center of the armature, the abutting faces may be set in appropriateportions in the bore surface of the armature.

FIG. 23 is a sectional view of a still further embodiment of an armaturefor a revolving electric machine to which the present invention relates.

An armature 520 of this embodiment has a groove 521 which is providedaround the periphery of the bore surface 504 thereof and a resin film506 which is provided at an angle with starting from the groove 521 inthe same way as the above-described embodiment. Since other members arethe same as those of the above-described embodiment, they are denoted bythe same reference numerals and are not described below.

The molding of the armature 520 can be performed by using the same moldsas those used in the above-described embodiment. The armature 520 canalso be obtained by previously providing a tape or a member 522comprising an elastic ring having heat resistance (for example,polyimide) on a butting face 513a between an upper mold 510 and a lowermold 511, injecting molding resin to bury armature winding 502 in theresin by molding, and removing the member 522.

Since the armature of this embodiment has the bore surface which isoutwardly inclined substantially from the center of the armature towardboth ends thereof, the armature can exhibit the same Function and effectas those exhibited by the above-described embodiment. In addition, sincethe elastic member having heat resistance is provided, the armaturewindings can be prevented from being deformed and pushed on the uppermold or the lower mold during molding even if the filling pressure ofthe molding resin is high, thereby the resin film 503 can be preciselyformed on the bore surface of the armature. When the armatureisassembled as a revolving electric machine, therefore, the armaturewindings are not deformed by vibration and heat generatd duringoperation and thus do not impair the fuction of the electric device.Since the elastic member is provided on the butting surface between theupper mold and the lower mold, no burr occurs in the butting portion,resulting in the possibility of precisely combining with a stator or thelike.

What is claimed is:
 1. A mold capable of forming a coreless armaturehaving a plurality of windings, comprising:a lower mold having a moldcavity therein, said mold cavity having an opening at an upper surfaceof said lower mold; a shaft adapted for supporting a plurality ofwindings of a coreless armature, said shaft receivable in the moldcavity of said lower mold; an upper mold for depositing molding materialinto the mold cavity of said lower mold; and an elastic ring plate beingpositioned about the opening of said lower mold and adapted forcontacting terminal ends of the windings extending outside of the moldcavity, said elastic ring plate further adapted to seal said mold cavitywith the terminal ends extending therefrom.
 2. The mold of claim 1,wherein said lower mold includes slits in its upper surface forreceiving terminal ends of the windings, and said elastic ring plateadapted to seal about the terminal ends received in the slits.
 3. Themold of claim 1, wherein said elastic ring plate comprises two adjacentconcentric rings, said adjacent rings adapted for receiving betweentheir adjacent surfaces the terminal ends of the windings.
 4. The moldof claim 3 wherein the internal diameter of the elastic ring plate beingsmaller than the diameter of the opening of the mold cavity in saidlower mold.
 5. The mold of claim 1, wherein said elastic ring platebeing positioned on the upper surface of said lower mold, and saidelastic ring plate being adapted to receive at its upper surface theterminal ends of the windings.
 6. The mold of claim 1, wherein saidshaft being positioned in said mold cavity and having an upper surfaceat the opening of the lower mold, and said upper surface of said shaftbeing coplanar with the upper surface of said lower mold.
 7. The mold ofclaim 1, wherein said shaft having an upper surface, and a thin filmmember being positioned on the upper surface of said shaft to preventdamage to said shaft when said shaft being in compressionalrelationships with said upper mold.
 8. The mold of claim 1, wherein saidelastic ring plate is affixed to the upper mold.
 9. The mold of claim 1wherein said lower mold includes a plurality of mold pieces, said moldpieces having registering faces by which each said mold piece contactsanother mold piece.
 10. A mold capable of forming a coreless armaturehaving a plurality of windings, comprising:a lower mold having a moldcavity therein, said mold cavity having an opening at an upper surfaceof said lower mold; a shaft adapted for supporting a plurality ofwindings of a coreless armature, said shaft receivable in the moldcavity of said lower mold; an upper mold for depositing molding materialinto the mold cavity of said lower mold; and an elastic ring plate beingpositioned about the opening of said lower mold and opposite said uppermold, and adapted for being compressed between said lower and uppermolds, said elastic ring plate further adapted to contact and cooperatein positioning terminal ends of the windings as they extend outside ofthe mold cavity, and to seal during molding the mold cavity with theterminal ends extending therefrom.
 11. A mold capable of forming acoreless armature having a plurality of windings, comprising:a lowermold having a plurality of mold pieces, said mold pieces havingregistering forces by which each said mold piece contacts another moldpiece, said lower mold with said contacting mold pieces defining a moldcavity therein which is open at an upper surface of said lower mold; ashaft adapted for supporting a plurality of windings of a corelessarmature, said shaft receivable in the mold cavity of said lower mold;an upper mold for depositing molding material into the mold cavity ofsaid lower mold; and an elastic ring plate disposed about the opening ofsaid lower mold and opposite said upper mold, and adapted for beingcompressed between said lower mold and said upper mold during molding,said elastic ring plate further adapted for contacting terminal ends ofthe windings as they extend outside of said mold cavity, and for sealingsaid mold cavity so that there is no leakage of molding material fromthe terminal ends as they extend outside of the mold cavity.